Welsh crooner Tom Jones was forced Thursday to cancel shows in Singapore and South Korea after doctors warned he risked "serious permanent damage" to his legendary vocal chords if he performed.

The ageing sex symbol was due to perform at Singapore's Resorts World Sentosa casino resort on Thursday evening, and in Seoul on Saturday.

The 69-year-old star, whose hits include "It's Not Unusual" and "Delilah", has been laid up in Singapore for a week after abruptly cutting short a previous show last Friday because of acute laryngitis.

"Due to doctor's orders, it is with deep regret that we have been forced to cancel tonight's performance in Singapore at Resorts World Sentosa and Saturday's show scheduled for Seoul, Korea at the Olympic Fencing Stadium," Tom Jones' management said in a statement.

"Sir Tom has been resting his voice all week in Singapore, with regular checkups with local specialists. Unfortunately, the doctors are nevertheless unable to guarantee that Sir Tom would be able to perform the full show tonight at 100 percent vocal strength," it said.

"In addition, they have warned that by performing, Sir Tom could risk serious permanent damage to his vocals."

Last week, he sang only two songs before begging off.

His management said it was "deeply sorry" for disappointing fans and hoped that the singer would "find a time to come back in the near future and reschedule the shows".

Resorts World Sentosa, wishing Jones a full recovery, apologised to ticket holders and said they would be refunded.

After Asia, Jones was scheduled to head onto South Africa next week for a pair of concerts in Cape Town and Johannesburg. There was no immediate word on whether the trip would go ahead.